Recently, the LED using a GaN semiconductor has been predominantly expected to replace existing light sources such as incandescent lamps, fluorescent lamps and mercury lamps. Thus, researches on a high-power GaN LED have been intensively made. In general, a substrate used for manufacturing a GaN LED is configured in such a manner that an n-type GaN 12, undoped InGaN (an active layer; 14) and a p-type GaN 16 are sequentially grown on a sapphire substrate 10, as shown in FIG. 1. Since the sapphire substrate 10 is non-conductive, the LED element typically has a horizontal structure as shown in FIG. 2. Here, reference numerals 18, 20, 22 and 24 denote a P-type transparent electrode, a P-type pad, an N-type electrode and an N-type pad, respectively.
In such a case, when it is in a high-power operation, the current spreading-resistance is high, and thus, its optical output is degraded. In addition, heat generated when the element is operated cannot be smoothly removed and thus thermal stability of the element is degraded to thereby cause a problem related with the high-power operation. In order to overcome this problem and implement a high-power GaN LED, a flip-chip LED using a flip-chip packaging method has been proposed and currently used. In the case of a flip-chip LED shown in FIG. 3, light emitted from the active layer 14 is emitted through the sapphire substrate 10. Therefore, since a thick p-type ohmic electrode 19 can be used instead of a transparent electrode 18, its current spreading-resistance can be reduced. Here, reference numerals 25, 30 and 32 denotes a solder, a heat sink and a conducting mount, respectively. However, since the flip-chip structure must be packed in the form of a flip-chip, the manufacturing process is complicated. In addition, since a large amount of light emitted from the active layer 14 is absorbed in the sapphire while the light is being emitted through the sapphire substrate 10, its optical efficiency is also degraded.